PCB congener distribution in estuarine water,sediment and fish samples: implications for monitoring programs

Traditional analyses for PCBs in environmental matrices havefocused on commercial Aroclor mixtures with detection limits inthe 100 to 1000 part per trillion range. This approach hasrecently been supplanted by analyses for specific PCB compoundscalled congeners with detection limits less than 0.5 ppt. At thenational level, total PCB determinations based upon selected PCBcongeners typically characterize analyses of surface water,sediment and tissue. These federal efforts rely on a suite of 18to 20 congeners out of a total of 209 congeners to characterizetotal PCB. The present study compares total PCB estimates basedupon this subset of congeners with estimates based upon anexpanded list of 81 congeners from water, sediment and fishtissue collected from the Delaware Estuary.Analytical data from monitoring programs conducted in theDelaware Estuary by the Delaware River Basin Commission, NOAANational Ocean Service, U.S. Army Corps of Engineers and the U.S.Environmental Protection Agency from 1996 to 1998 were evaluated. Total PCB estimates derived from the different sets of congeners,including the adjustment factor of 2.0 used by NOAA, werecompared. This evaluation indicated that differences existbetween total PCB determinations based upon these approaches, andthat these differences vary depending on the matrix analyzed. The bias associated with using a smaller set of PCB congeners,and the implications for risk assessment are discussed.     

Mortality,violence and lack of access to healthcare in the Democratic Republic of Congo

The people of the Democratic Republic of Congo for decades have been living in a situation of chronic crisis. Violence, population displacement and the destruction of infrastructure and health services have devastated the health of the population. In 2001, Médicins Sans Frontières conducted a survey in five areas of western and central DRC to assess mortality, access to health-care, vaccination coverage and exposure to violence. High mortality rates were found in front-line zones, mainly due to malnutrition and infectious diseases. In Basankusu approximately 10 per cent of the total population and 25 per cent of the under-five population had perished in the year before the survey. Humanitarian needs remain acute across the country, particularly near the front line. Infectious-disease control and treatment are a priority, as is increasing access to health-care. Humanitarian assistance must be increased considerably, especially in rural areas and zones that have been affected directly by conflict.     

Nitrate losses in subsurface drainage from a corn-soybean rotation as affected by time of nitrogen application and use of nitrapyrin

Subsurface drainage, a water management practice used to remove excess water from poorly drained soils, can transport substantial amounts of NO3 from agricultural crop production systems to surface waters. A field study was conducted from the fall of 1986 through 1994 on a tile-drained Canisteo clay loam soil (fine-loamy, mixed, superactive, calcareous, mesic Typic Endoaquoll) to determine the influence of time of N application and use of nitrapyrin [NP; 2-chloro-6-(trichloromethyl) pyridine] on NO3 losses from a corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation. Four anhydrous ammonia treatments [fall N, fall N + NP, spring preplant N, and split N (40% preplant and 60% sidedress)] were replicated four times and applied at 150 kg N ha(-1) for corn on individual drainage plots. Sixty-two percent of the annual drainage and 69% of the annual NO3 loss occurred in April, May, and June. Flow-weighted NO3-N concentrations in the drainage water were two to three times greater in the two years following the three-year dry period compared with preceding and succeeding years. Nitrate N concentrations and losses in the drainage from corn were greatest for fall N with little difference among the other three N treatments. Nitrate losses from soybean were affected more by residual soil NO3 following corn than by the N treatments per se. Averaged across the four rotation cycles, flow-normalized NO3-N losses ranked in the order: fall N > split N > spring N = fall N + NP. Under these conditions NO3 losses from a corn-soybean rotation into subsurface drainage can be reduced by 13 to 18% by either applying N in the spring or using NP with late fall-applied ammonia.     

Hormesis and stage specific toxicity induced by cadmium in an insect model,the queen blowfly,Phormia regina Meig

Hormesis is an adaptive response, commonly characterized by a biphasic dose-response that can be either directly induced, or the result of compensatory biological processes following an initial disruption in homeostasis [Calabrese and Baldwin, Hum. Exp.Toxicol., 21 (2002), 91]. Low and environmentally relevant levels of dietary cadmium significantly enhanced the pupation rate of blowfly larvae, while higher doses inhibited pupation success. However, dietary cadmium at all exposure levels adversely affected the emergence of the adult fly from the pupal case. Such findings represent the first report of a heavy metal displaying a hormetic-like biphasic response for pupation success, while at the same time displaying stage-specific toxicity at a later developmental period.These conclusions are based on substantial experimentation of over 1750 blowflies, in seven replicate experiments, involving 10 concentrations per experiment. These findings indicate the need to assess the impact of environmental stressors over a broad range of potential exposures as well as throughout the entire life cycle.     

An environmental assessment of enhanced oil recovery

The objective of this assessment is to quantify some of the environmental effects of a significant increase in United States oil production by tertiary or enhanced oil recovery (EOR) methods. The problems associated with each EOR technology are discussed and controls and regulations are briefly summarised. A tertiary oil production scenario for the United States was developed focussing only on mainland fields in the lower 48 states. It included all of the EOR methods expected to be in use during the next two decades. The environmental impacts, including water requirements, air emissions and generation of solid wastes, are then scaled to this scenario. The effects of control technologies and state regulations are considered. A comparison is also made between the impacts of EOR as an energy source and impacts associated with coal and synthetic fuels which concludes that EOR is preferable in many respects. There are environmental risks associated with EOR technologies, specific projects and specific fields in the production scenario; however, most problems are solvable by responsible regulation, enforcement of regulations and application of the best professional engineering by project operators.     

Empowered native community, modified SIA: The case of hydaburg, alaska

This paper reviews a social impact assessment of Hydaburg, Alaska, to illustrate the modifications of non-NEPA SIAs in response to “empowered” Native communities. Hydaburg has been influenced by three organizations designed to promote greater self-determination: the Native Village Corporation, a Native municipal government, and the Native Sovereignty Movement. The Hydaburg SIA incorporated community-based research, cultural assessment, and advocacy mitigation to accommodate the demands of this“empowerment”. The paper suggest that modified SIAs of this sort are likely to become more prevalent as self-determination among Native communities increases.     

Design guidelines for an optimum scrubber system

The revised New Source Performance Standards (NSPS) for the utility industry mandates reduced particulate matter and sulfur dioxide emissions from new utility boilers. A wet scrubber system can be an advantage in controlling both of these emissions. Existing wet scrubber systems may meet the new standards with significant increase in power consumption. A careful design of the entire scrubber system, based on the experience gained at the existing installations, is necessary to ensure cost effectiveness. The experience with existing wet scrubber systems used on coal-fired utility boilers is reviewed and their performance is correlated with power consumptions. Based on a correlation of scrubber pressure drop against outlet concentration, conventional scrubber systems would be able to meet the revised NSPS for particulate matter with a theoretical scrubber pressure drop of 43±5 cm H₂O. Overall system pressure drop, however, could easily run as high as 76 cm H₂O. Novel scrubber systems such as the electrostatically augmented scrubber may provide the necessary collection performance at lower pressure drops. The performance of the various scrubber components such as mist eliminators and reheaters is reviewed. Operating problems are also discussed.     

USE OF SYNOGRAPHIC TECHNIQUES IN RESEARCH AND DISSEMINATION OF HYDROLOGICAL INFORMATION1

ABSTRACT: Application of synographic techniques to four separate nonrelated research tasks demonstrated the usefulness of such an approach in interpreting and communicating hydrologic survey data especially when large geographic areas are involved. Nutrient exchange and biotic indicators in coastal estuaries were analyzed to determine residence times in different seasons of the year. Man induced changes in urban runoff patterns were shown to increase the probability of flooding with different recurrences of storm events. Nitrate and indicator bacteria in private wells were analyzed on a county-wide basis to determine the sources and extent of natural occurrence versus contamination origins. Water wells and the surface supply of metropolitan Houston were analyzed for sodium content to assist citizens and physicians with data which are needed for derivation of sodium restricted therapeutic diets.     

UNSATURATED FLOW THROUGH SOLID WASTE LANDFILLS: MODEL AND SENSITIVITY ANALYSIS1

ABSTRACT: The movement of precipitation water infiltrating through the material (refuse) of solid waste landfills is examined via numerical solution of the equations of continuity, and motion (Darcy's Law). The solution of the equations is obtained by a fully implicit, finite-difference scheme. Both unsaturated and saturated surface conditions are considered, making the scheme suitable for real-time simulation of net precipitation and moisture redistribution events. A sensitivity analysis showed that for unsaturated surface conditions the solution is primarily affected by hydraulic conductivity and capillary diffusivity, and is relatively independent of the space and time steps. In addition, the precipitation averaging process is shown to be critical in the correct computation of moisture transport during the time period where the transition from unsaturated to saturated conditions occurs. The model presented herein is suitable for analysis of water movement through landfills, and the design of bottom collection systems.